An income of $250,000 a year “is dead as the dividing line” for distinguishing the middle class in extending the Bush tax cuts, the centerpiece issue of the upcoming lame-duck session of Congress, Democratic aides have said.

Instead, negotiations will begin around a threshold of $500,000 or $1 million, the aides said.

President Barack Obama said this week that he would make a new push to protect the middle class from the tax cuts’ scheduled expiration at the end of this year.

The new figures means a broader swath of Americans would be considered “middle class” during the negotiations.

“A higher threshold is more inclusive and doesn't make an enemy out of households that may be slightly above $250,000, but are still firmly in the middle class,” a senior Hill aide explained. “It also simplifies the contrast message, by making it clear what Republicans are fighting for: a tax cut that is literally for millionaires.”

Democrats say that even if the figure went as high as $1 million, the result would still be very helpful to deficit reduction because the bulk of the cost of extending the Bush tax cuts comes from those who make more than $1 million, not those from $250,000 to $1 million.

The aides also said that the administration wants to “decouple” the middle- and upper-class extensions, with a permanent extension for the middle class and a temporary extension for the top tier.

“Its big selling point is that, as long as middle-class and upper-income tax cuts are linked, GOP will always have leverage to extend the less popular upper income tax cuts by holding the very popular middle class tax cut hostage,” the aide said.

“So, the idea is to put them on different timelines, with different expiration dates. If, in two years, the only thing expiring is the tax cuts for the wealthy, it will be easy to let those expire. But if we've extended everything (middle class and wealthy) together, then in a year or two we will be in the same situation where the GOP won't extend the cut for the middle class unless the wealthy get included.”